EP0487805A1 - Rope made from composite material - Google Patents

Abstract

Rope made from composite material, intended more particularly to serve as a semi-rigid or rigid guy, and characterised in that it consists of a filamentary winding of composite fibre agglomerated by means of a binding agent and wound according to a plurality of possible arrangements about at least two end spindles forming at least two corresponding end heads, each having an orifice or taking the form of a ball, so as to make it easier to fasten the rope. <IMAGE>

Description

The present invention relates to a rigid or semi-rigid cable made of composite material, more particularly intended to serve as a shroud, and which has unequaled technical characteristics in particular in the shrouding range, ranging from lightness and solidity, and capable of withstanding high tensile stresses. According to other possible uses, the invention also relates to nautical equipment such as halyards, shackles, articulation cords and more generally any type of ropes used on sailboats.

• la carbone est obligatoirement enduit de résine pour être solide,
• le KEVLAR est plus élastique, sensible à l'humidité et perd ses qualités aux rayonnements ultra-violets,
• le SPECTRA ou DYNEMA sont affectés par du fluage au cours du temps et ne peuvent être collés que par un adhésif qui reste toujours gluant.

Traditionally, cables made of composite material used in the field of sailing consist of a central part, the cable itself, to which are attached at each end of the end pieces allowing the cable to be fixed at its two ends. The composite fibers used are made of carbon or glass, or else of synthetic materials sold under brands such as: SPECTRA, DYNEMA or KEVLAR. These fibers are coated with resin. However, these materials used have different characteristics which require special treatments and which make them suitable for different applications:

• carbon must be coated with resin to be solid,
• KEVLAR is more elastic, sensitive to humidity and loses its qualities to ultraviolet radiation,
• SPECTRA or DYNEMA are affected by creep over time and can only be glued with an adhesive which always remains sticky.

The type of configuration mentioned, however, presents a major defect: the heterogeneity between the intermediate part, the cable as such, and the two reported end fittings. The first problem concerns the differences in weight, material, structure between these elements, which are likely to weaken their connection. Secondly, the very fixing of the end-piece to the end of the cable constitutes a technical problem which is difficult to solve, due to the particular constraints to which these cables are subjected.

These pitfalls are particularly troublesome in the framework of the guying, which is the preferred example that we will use in this text, applied to the requirements of the world of sailing. Indeed, due to the large tensile forces exerted on the shrouds of a sailboat, in particular if its sail is substantial, it is necessary to use shrouds of fairly large diameters. The corresponding end caps, dimensioned to adapt to the constraints laid down, are therefore of such bulk that the weight gain due to the cable is lost and that the problems of fixing between the end caps and the cable are enormous and prohibitive.

• des embouts à cône de serrage,
• des systèmes à collage, et
• des dispositifs à filetage, pour ne citer que les plus courants.

There are indeed several types of tips conventionally used:

• clamping cone tips,
• bonding systems, and
• threaded devices, to name just the most common.

In the first case, the connection causes radial compression forces of the fiber which can - depending on the value of the angle - be ten times greater than the tensile load. However, the composite fibers do not support the lateral loads, and said load being in principle the expression of the effort to contain, we can well measure the ineffectiveness of this first system, due to a significant loss compared to the cable load.

The second device has an imbalance between the external and internal fibers of the cable, due to the bonding which only affects the external "skin". The risks of detachment are also significant and can only be combated by the use of tips offering a sufficient bonding length, therefore of space and weight out of proportion to the required objectives. This configuration also leads to problems of expansion of the different materials.

However, it is possible to obtain a larger bonding surface and thus to achieve a more homogeneous bond by recasting or opening the fibers of a cable produced by pultrusion. But this is only valid with carbon fibers, where it can be effective.

Finally, the third type of tip is too dependent on the quality of the resin, since the solidity of the assembly is dependent on it: the fibers are of course cut with each thread. In addition, bottom-of-shear problems can arise if the tip is not properly sized. Again, only bulkheads such as weight reduction targets cannot be achieved provide sufficient strength guarantees.

In any event, technical solutions, when they exist, are not the simplest to implement and therefore often expensive.

• d'une part offrir une résistance maximale aux contraintes de traction,
• conserver d'autre part autant que possible une structure légère, autant dans son encombrement que dans son poids, et
• satisfaire à ces solutions techniques sans aboutir à des coûts prohibitifs.

These examples clearly show that the major problems to be resolved are apparently quite antagonistic:

• on the one hand, offer maximum resistance to tensile stresses,
• on the other hand, keep a light structure as much as possible, both in its size and in its weight, and
• satisfy these technical solutions without leading to prohibitive costs.

The cable according to the invention overcomes the drawbacks mentioned by proposing an original structure which makes it possible to overcome the listed problems.

The theoretical analysis of failures resulting from the designs of the prior art made it possible to isolate a constant characteristic of these systems: the tensile forces apply to the cables, in each of the cases mentioned, at a point external to the bundle of fibers. , so that the interfacing between the ends and the bundle is extremely difficult to achieve, for all the reasons mentioned above.

The weak points of the assembly are not located at the level of the composite fibers proper, whereas it would be, if this were the case, easy to adapt the beam to the tensile force exerted, without increasing the volume. or the weight of the system unreasonably.

On the contrary, it is necessary to modify the dimensioning of the ends, with the results that we know, so that the structure is mechanically viable.

The shrouds of the invention are based on the opposite principle: it is the fibers which collect the major part of the efforts, helping to facilitate the adaptation of the assembly to the conditions of use without leading to aberrant configurations.

The points of application of the tensile forces are not placed outside the bundle of fibers, but conversely, they are located inside said bundle.

To this end, the invention also provides a cable of composite material, flexible or rigid, and intended more particularly for guying, but which is characterized in that it consists of a filament winding of composite fiber agglomerated by means of connection, and wound in several possible arrangements around at least two end axes forming at least two corresponding terminal heads, each having an orifice or taking the form of a ball in order to facilitate the fixing of the cable.

These terminal heads are moreover provided with means intended to distribute and / or absorb the forces exerted on the cable, and the winding can be coated with an additional protection means.

Of course, the composite fibers constituting the cable proper, as well as the binders or connecting means, can be chosen from a few materials usually used in this type of technology. Several examples will be given later in this text. The connecting means can thus be applied cold or hot.

The winding itself can undergo variants. In the simplest case, it is a simple winding around several axes, respecting the geometrical layout of the shroud to be manufactured. But it is also possible to twist the winding of the fiber during winding, in order to increase the tensile strength of the cable.

For the same purpose, it is possible to wind the wire according to a radial wire drawing in order to connect the longitudinal unidirectional fibers together. This can be done in a second step, after completing the axial winding.

In order to adapt to the context of use, the cable can also adopt a form of lenticular section, which may in particular be required on sailboats intended to participate in sports competitions.

Furthermore, as we have seen, several combinations of materials are possible, since there is a choice to be made for the fibers and for the binding medium. One of the consequences is the possibility of obtaining flexible or rigid shrouds, depending on the combination chosen and the characteristics of the product expected.

The product obtained can be coated with a protective sheath or painted, so as to improve its surface condition for particularly aesthetic reasons, but also to preserve the condition of the cable. In fact, certain resins which can be used as a binder are sensitive to ultraviolet radiation, and can be deteriorated after a certain period of exposure. This risk should therefore be prevented by adopting one of the means of protection mentioned. In addition, a sheath can prove to be a valuable aid against accidental side impacts.

One of the main advantages of the design according to the invention is the adaptability to any type of configuration. It is indeed an extremely light homogeneous assembly, due to the absence of attached end caps, and very reliable since the forces in each fiber are characterized by continuity and optimal distribution. This type of design is moreover not limited by dimensional problems, as was the case until now.

On the contrary, shrouds supporting high loads can be manufactured by increasing the number of passes during winding. Thus, this type of shroud results from a manufacturing process which is extremely flexible and adaptable to each use case.

However, although the structure even in filament winding is extremely reliable, additional means have been provided for distributing and absorbing the forces exerted.

According to a first means, the end orifice is surrounded by a ring, for example made of stainless steel, around which the fibers are wound. The longitudinal forces are thus better distributed around the periphery of the ring, and better transmitted to the fibers.

An additional means consists in surrounding the steel ring with a carbon "cushion", in reality a second kind of ring, whose properties are a little different, and which is used not only to distribute the forces, but also to damp them. In this way, the terminal structure thus produced is much more flexible than in the previous configurations. It is of course possible to place one or more carbon "cushions", depending on the expected effects.

In an even more sophisticated configuration, each terminal head is provided with several auxiliary axes allowing a differentiated winding on heads which are in fact multidimensional. This type of design allows fine adjustment, suitable for any type of product.

The cable end of the invention can also be produced in the form of a ball provided with a central core, at the end axis, and a secondary axis around which part of the winding is formed. . Additionally, at the level of the flare marking the intersection between the central body of the cable and the end ball, a support cup is added.

Finally, it is possible to make guy lines allowing multiple guy lines by diverting the main cable in one or more places, in directions diverging from the main longitudinal axis.

According to another application, it is possible to make halyards or other mobile rope which are not then coated with resin. Consequently, they cannot be made of carbon fiber which is necessarily coated therewith. The general diagram is the same, with a splice or a knot before the terminal ends, to fix the winding at said ends.

However, it should be noted that the addition of a knot results in a loss of 40% of the resistance, while a splice gives an excellent result. Concretely, we can make a halyard in SPECTRA or KEVLAR with 80% of the longitudinal parallel fibers, 20% of braided sheath. The turn around the fulcrum, at the end axis, is followed by a long splice: the result is quite convincing.

Another variant of the invention relates to a shackle or an articulation cord. The cable is folded back on itself, so that the terminal openings are coaxial, thus forming a shackle or a cord. The fibers form a dead turn of the thread of the axis serving as a mandrel and mold, allowing the threaded part to be obtained without requiring machining and without cutting fibers.

These shackles are excellent, reliable and very economical. They are also light, but must be protected at the top.

• la figure 1 schématise la structure basique avec bobinage simple entre deux axes,
• la figure 2 schématise un bobinage avec un ou plusieurs tours morts à chaque extrémité, et adjonction d'une bague en acier inoxydable et d'un "coussin" carbone,
• la figure 3 est une représentation d'un système comprenant des axes de bobinage annexes,
• la figure 4 montre une tête terminale avec transfilage radial,
• la figure 5 représente un bobinage torsadé,
• les figures 6 et 7 montrent deux haubans terminés, dont l'un avec une dérivation,
• la figure 8 représente un schéma partiel du hauban à boules terminales, et
• la figure 9 donne un exemple illustré de réalisation de manille.

In the following, the object of the invention will be described in detail by giving some specific examples, and with particular reference to the appended figures, for which:

• FIG. 1 schematizes the basic structure with simple winding between two axes,
• FIG. 2 shows diagrammatically a winding with one or more dead turns at each end, and the addition of a stainless steel ring and a carbon "cushion",
• FIG. 3 is a representation of a system comprising annexed winding axes,
• FIG. 4 shows a terminal head with radial threading,
• FIG. 5 represents a twisted winding,
• Figures 6 and 7 show two completed guy lines, one of which has a branch,
• FIG. 8 represents a partial diagram of the stay cable with end balls, and
• Figure 9 gives an illustrated example of a shackle embodiment.

Examination of all of these figures clearly shows how multiple the combinations of embodiments are, depending on whether one adopts one or the other of the structures mentioned, and / or whether they are mixed so as to obtain a result corresponding well to mechanical reality during use.

Figure 1 shows the general principle of the shrouds according to the present invention, for which the composite fiber (1) is wound around two axes (2) (2 ') whose spacing constitutes the length of the shroud.

Figure 2 differs in that, at each axis, one or more dead turns are made so as to create a better distribution of forces at this level. This is further reinforced by the addition of a ring (3) made of stainless steel, or any other suitable metal, and a cushion (4) made of carbon.

FIG. 3 represents a possible configuration of the multi-axis variant, in which each terminal head is provided with its two main axes (2) (2 '), then secondary or annex axes (3) and (3'), (4) and (4 ') ... The winding around these axes can either be simple or include turns dead, as the case may be. The material substrate allowing multiple winding is obtained with an encarbone lug, and stainless steel rings.

Figures 4 and 5 show two possible variants of winding, respectively with a radial wire drawing and a twisted winding. This makes it possible, in combination with the connecting means, to increase the resistance of the stay cable, in particular to traction.

It should be noted that the resins do not hold onto the radial threads, which are therefore used in the flexible stays, with a sheath. The ends can however be coated with resin to solidify the whole.

With regard to the particular case constituted by SPECTRA, of which it has been said that the slippery fibers are unbondable and are subject to creep, said fibers are braided parallel, resinated at the ends so as to bind them together, and sheathed or threaded in a braid at more or less 45 ° braiding angle for their flexible part.

Finally, Figures 7 and 8 show two possible examples of guy lines used on sailboats. The first is as simple as possible, while the second has a derivation. It goes without saying that such a shroud may well have several branches, depending on the use which is intended for it. The limitations to these types of configuration, however, come from mechanical tests: they must of course resist the various constraints to which they will be subjected during real use, namely tensile, bending, or even shear stresses in certain cases.

According to the first example of structure used, the composite fiber is a thermoplastic fiber of the type sold under the brand SYSTEM FIT, which can be applied to any type of fiber surrounded by thermoplastic powder, acting as a binder. The strop used for the test is rolled up hot, the thermoplastic being melted just before winding.

This type of guy, however, has a point of weakness at its extreme point, at the intersection with the longitudinal axis, when it is of the type shown in Figure 1, that is to say made with a single coil.

The second example is made with fibers marketed under the brand SPECTRA, and with glue marketed under the brand NEOPRENE as a binder. The fiber is impregnated manually, and the winding takes place cold between the axes.

The tensile strength is excellent: this type of shroud withstands traction reaching 45,000 N, for a strop 20 cm long with a diameter of 13 mm and weighing 200 g. Incidentally, it should be noted that this result is obtained with a guy wire which is extremely light, due to its constituents.

In the third example, it is carbon fibers, with epoxy resin as a binder. In this case, a carbon "cushion" has also been added to a metal ring and the winding involves several dead turns on each pass, with the lowest possible tension for the wire during the winding of said dead turns.

In practice, it turns out that the breaking tension is approximately 100,000 N, which is also excellent. The result can be further improved by strengthening the side of the terminal heads which turns out to be the weak point where the rupture occurs.

Finally, the last example concerns a device as shown in Figure 3, that is to say multi-axis. The material to be wound is fibrocarbon, and the binder is again epoxy-type resin. The different axes 2, 3, 4, 5 and 2 ', 3', 4 ', 5' allow a declining winding with smaller and smaller cushions.

• 30 tours morts sur le système d'axes (2+3)
• 30 tours morts sur le système d'axes (2+4)
• 30 tours morts sur le système d'axes (2+5)
• 60 tours entre les deux têtes terminales.

According to the example taken to make the full test, we have achieved:

• 30 dead turns on the axis system (2 + 3)
• 30 dead turns on the axis system (2 + 4)
• 30 dead turns on the axis system (2 + 5)
• 60 turns between the two terminal heads.

This amounts to considering that there are 180 fibers passing through the end, at point I, and 60 fibers multiplied by 2 in J.

The resin is then baked in the oven for one hour. The result obtained therefore has an excellent finish.

Figure 8 shows the ball end variant. The core (10) can be made of fiber or other materials, depending on the use. The support cup (11) follows the flare of the end ball and is currently provided in stainless steel or titanium.

The secondary axis (12) is placed in the main body of the cable, at a certain distance from the end piece.

• on réalise 60 tours pour le noyau/coussin,
• 30 tours entre le noyau (10) et l'axe secondaire (12) par des fibres dites de renfort,
• 30 tours de fibres dites "ravaillantes" entre les deux extrémités.

The example tested for this configuration is as follows:

• 60 laps are made for the core / cushion,
• 30 turns between the core (10) and the secondary axis (12) by so-called reinforcing fibers,
• 30 towers of so-called "refreshing" fibers between the two ends.

Figure 9 schematically shows a shackle. One or more of the end ports (13) are molded around a threaded mandrel, which threads the port without severing the fibers. The general configuration of this shackle is however very close to a standard cable, the difference being that the end heads are placed opposite one another.

In general, the fibers used can be chosen from materials such as carbon, aramid fibers consisting of polyparaphenyleneterephthalamide, for example sold under the trademark KEVLAR, or fibers known by the trademark SPECTRA. As for the binders, they can be chosen from synthetic resins such as epoxy or epoxy resins, or from synthetic elastomeric adhesives, for example based on polychloroprene such as that which is marketed under the brand NEOPRENE.

The cables of the present invention offer technical qualities which have had no equivalent in this field. They are light and resistant to tensile stresses, and are therefore suitable for use, for example, on racing yachts. In general, they respond to a constant concern of naval architects which consists in improving the performance of sailboats, thereby subjecting the components to more and more intensive efforts, while tending to reduce the weights and dimensions of said constituents.

Another major advantage of the cables of the invention is that they can easily be repaired, even at sea, without the support of a well-equipped workshop. Indeed one can use resins which are compatible with water, and in particular sea water, authorizing repairs at any time, for example in full race if they are competition boats.

Of course, the invention is not limited to the examples given previously, which serve only to illustrate the description; on the contrary, it encompasses all variants which proceed from the same spirit.

Claims (25)

Cable made of composite material more particularly intended to serve as a shroud, semi-rigid or rigid, and characterized in that it consists of a filament winding of composite fiber agglomerated by a bonding agent, and wound in several possible arrangements around d 'at least two end axes, forming at least two corresponding terminal heads each comprising an orifice or taking the form of a ball in order to facilitate the fixing of the cable. Cable according to claim 1, characterized in that the terminal heads are provided with means intended to distribute and / or absorb the forces exerted on said cable. Cable according to either of Claims 1 and 2, characterized in that the means for distributing the forces for a head provided with an orifice consists of a ring centered on the end axis and around which pass the winding fibers. Cable according to claim 3, characterized in that the rings are made of stainless steel. Cable according to any one of claims 2 to 4, characterized in that the means of absorbing the forces exerted on the cable consists of one or more carbon cushion (s) placed (s) around the ring. Cable according to any one of Claims 2 to 5, characterized in that the terminal heads are provided with one or more annexed winding axes allowing differentiated winding on multidimensional heads. Cable according to any one of the preceding claims, characterized in that the winding is twisted. Cable according to any one of claims 1 to 6, characterized in that the fibers are wound according to a radial transfilage connecting the longitudinal unidirectional fibers to each other. Cable according to any one of the preceding claims, characterized in that the body of said cable has a shape of lenticular section. Cable according to any one of the preceding claims, characterized in that the winding comprises one or more dead turns around the terminal heads. Cable according to any one of the preceding claims, characterized in that the main cable comprises one or more branch (s) allowing multiple guying and developing in directions diverging from the main longitudinal axis. Cable according to any one of claims 1, 2, 6, 10, characterized in that the end balls are provided with cores at the level of the end axes, and one or more secondary axes around which part of the winding. Cable according to the preceding claim, characterized in that the flare marking the intersection between the end ball and the central body of the cable is provided with a support cup. Cable according to any one of the preceding claims, characterized in that the winding is made of thermoplastic fiber agglomerated together when hot. Cable according to any one of Claims 1 to 13, characterized in that the fibers used are made of carbon. Cable according to any one of Claims 1 to 13, characterized in that the fibers used are aramid fibers consisting of polyparaphenyleneterephthalamide, of the type sold under the brand KEVLAR. Cable according to any one of the preceding claims, characterized in that the connecting means is a synthetic resin with which the composite fibers are impregnated, hot or cold. Cable according to the preceding claim, characterized in that the resin used to agglomerate and bind the fibers together is an epoxy type resin. Cable according to any one of claims 1 to 16, characterized in that the connection means is an adhesive of synthetic elastomer type. Cable according to claim 19, characterized in that the adhesive used is based on polychloroprene, of the type sold under the brand NEOPRENE. Cable according to any one of the preceding claims, characterized in that the winding is coated with an additional protection means. Cable according to claim 21, characterized in that the protective means is a sheath covering the length of the cable. Cable according to claim 23, characterized in that the protective means is a paint protecting the binder against ultraviolet radiation. Cable according to one of claims 1 or 2, characterized in that the two end orifices are coaxial, the two end heads being placed opposite one another. Cable according to the preceding claim, characterized in that one or more of the orifices are threaded.

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